Field of the Invention
An aspect of the present invention relates to a secondary battery, and more particularly, to a secondary battery in which a gasket remains durable, i.e., maintains its durability, while being melted by internal heat generation to prevent the secondary battery from being short-circuited.
Description of the Related Art
High power lithium secondary batteries used for electrical power tools require large current discharge because of their environmental characteristics. Particularly, a cylindrical high power secondary battery has an electrode tab with a limited width, therefore, a very large amount of heat is generated under the condition of large current discharge.
For example, instantaneous current or surge current that instantaneously flows in the cylindrical high power secondary battery may reach about 100 A. In this case, temperature increases rapidly at an electrode tab in the secondary battery. Therefore, a gasket interposed between a can and a cap assembly is melted, and thus, the can and the cap assembly (or a cap-up of the cap assembly) are short circuited to each other.